Double clutch transmission

Abstract

A double clutch transmission (DCT) provides eight forward speeds and one reverse speed while minimizing the number of gear trains used for changing speed and the whole length thereof. In particular, the DCT has a simple structure using four or five gear trains and four synchro devices and is capable of providing eight forward speeds and one reverse speed while reducing the entire weight thereof. In a conventional DCT, when a gear train is added to increase the number of speed stages, the whole length thereof is increased. The provided DCT can minimize the whole length and the weight thereof, thereby reducing the manufacturing cost, the number of parts, and the fuel efficiency.

The invention claimed is: 
     
       1. A double clutch transmission (DCT) which provides eight forward speeds and one reverse speed, comprising:
 first and second input shafts  10   a  and  10   b  selectively receiving power from an engine E/G through a first clutch C 1  and a second clutch C 2 , respectively; 
 an output shaft  20  including first and second output shafts  20   a  and  20   b  which receive power from the first and second input shafts  10   a  and  10   b , respectively, and output the received power; 
 first and second gear trains  30   a  and  30   b  mounted on the first input shaft  10   a  and selectively transmitting power to the output shaft  20 ; 
 third and fourth gear trains  30   c  and  30   d  mounted on the second input shaft  10   b  and selectively transmitting power to the output shaft  20 ; 
 a first synchro device  40   a  installed on the first output shaft  20   a  so as to be positioned between the first and second gear trains  30   a  and  30   b  and synchronizing the first and second gear trains  30   a  and  30   b  to selectively transmit power, and a third synchro device  40   c  installed on the first output shaft  20   a  so as to be positioned between the third and fourth gear trains  30   c  and  30   d  and synchronizing the third and fourth gear trains  30   c  and  30   d  to selectively transmit power; 
 a second synchro device  40   b  installed on the second output shaft  20   b  so as to be positioned between the first and second gear trains  30   a  and  30   b  and synchronizing the first and second gear trains  30   a  and  30   b  to selectively transmit power, and a fourth synchro device  40   d  installed on the second output shaft  20   b  so as to be positioned between the third and fourth gear trains  30   c  and  30   d  and synchronizing the third and fourth gear trains  30   c  and  30   d  to selectively transmit power; and 
 an output gear  50  installed on the output shaft  20  and transmitting an output thereof to a differential device Diff, 
 wherein at least one forward speed is configured to be determined by selecting at least two gear trains from the first to fourth gear trains  30   a  to  30   d,    
 wherein the first and second input shafts  10   a  and  10   b  are provided in the form of dual pipes using hollow shafts and arranged on a coaxial line, 
 wherein the first to fourth gear trains  30   a  to  30   d  comprise external gears, 
 wherein a speed change to a reverse speed is realized as the second clutch C 2  is operated, and the third synchro device  40   c  is engaged with the fourth gear train  30   d;    
 wherein a speed change to a neutral speed is realized as the second synchro device  40   b  is engaged selectively with the second gear train  30   b , and the fourth synchro device  40   d  is engaged with the fourth gear train  30   d;    
 wherein a speed change to a first forward speed is realized as the first clutch C 1  is operated, the second synchro device  40   b  is engaged with the second gear train  30   b , and the fourth synchro device  40   d  is engaged with the fourth gear train  30   d;    
 wherein a speed change to a second forward speed is realized as the second clutch C 2  is operated, and the fourth synchro device  40   d  is engaged with the fourth gear train  30   d,    
 wherein a speed change to a third forward speed is realized as the first clutch C 1  is operated, and the first synchro device  40   a  is engaged with the second gear train  30   b;    
 wherein a speed change to a fourth forward speed is realized as the second clutch C 2  is operated, and the third synchro device  40   c  is engaged with the third gear train  30   c;    
 wherein a speed change to a fifth forward speed is realized as the first clutch C 1  is operated, and the first synchro device  40   a  is engaged with the first gear train  30   a;    
 wherein a speed change to a sixth forward speed is realized as the second clutch C 2  is operated, and the fourth synchro device  40   d  is engaged with the third gear train  30   c;    
 wherein a speed change to a seventh forward speed is realized as the first clutch C 1  is operated, the second synchro device  40   b  is engaged with the first gear train  30   a , and the fourth synchro device  40   d  is engaged with the third gear train  30   c ; and 
 wherein a speed change to an eighth forward speed is realized as the second clutch C 2  is operated, the first synchro device  40   a  is engaged with the first gear train  30   a , and the second synchro device  40   b  is engaged with the second gear train  30   b.    
 
     
     
       2. A DCT which provides eight forward speeds and one reverse speed, comprising:
 first and second input shafts  10   a  and  10   b  selectively receiving power from an engine E/G through a first clutch C 1  and a second clutch C 2 , respectively; 
 an output shaft  20  including first and second output shafts  20   a  and  20   b  which receive power from the first and second input shafts  10   a  and  10   b , respectively, and output the received power; 
 first and second gear trains  30   a  and  30   b  mounted on the first input shaft  10   a  and selectively transmitting power to the output shaft  20 ; 
 third and fourth gear trains  30   c  and  30   d  mounted on the second input shaft  10   b  and selectively transmitting power to the output shaft  20 ; 
 a first synchro device  40   a  installed on the first output shaft  20   a  so as to be positioned between the first and second gear trains  30   a  and  30   b  and synchronizing the first and second gear trains  30   a  and  30   b  to selectively transmit power, and a third synchro device  40   c  installed on the first output shaft  20   a  so as to be positioned between the third and fourth gear trains  30   c  and  30   d  and synchronizing the third and fourth gear trains  30   c  and  30   d  to selectively transmit power; 
 a second synchro device  40   b  installed on the second output shaft  20   b  so as to be positioned between the first and second gear trains  30   a  and  30   b  and synchronizing the first and second gear trains  30   a  and  30   b  to selectively transmit power, and a fourth synchro device  40   d  installed on the second output shaft  20   b  so as to be positioned between the third and fourth gear trains  30   c  and    30 d  and synchronizing the third and fourth gear trains  30   c  and  30   d  to selectively transmit power; and 
 an output gear  50  installed on the output shaft  20  and transmitting an output thereof to a differential device Diff, 
 wherein the fourth gear train  30   d  comprises a fifth gear train  30   e  so as to operate as dual gear trains, 
 wherein the first and second input shafts  10   a  and  10   b  are provided in the form of dual pipes using hollow shafts and arranged on a coaxial line, 
 wherein the first to fourth gear trains  30   a  to  30   d  comprise external gears, 
 wherein a speed change to a reverse speed is realized as the second clutch C 2  is operated, and the third synchro device  40   c  is engaged with the fourth gear train  30   d;    
 wherein a speed change to a neutral speed is realized as the second synchro device  40   b  is engaged selectively with the second gear train  30   b , and the fourth synchro device  40   d  is engaged with the fourth gear train  30   d;    
 wherein a speed change to a first forward speed is realized as the first clutch C 1  is operated, the second synchro device  40   b  is engaged with the second gear train  30   b , and the fourth synchro device  40   d  is engaged with the fourth gear train  30   d;    
 wherein a speed change to a second forward speed is realized as the second clutch C 2  is operated, and the fourth synchro device  40   d  is engaged with the fourth gear train  30   d;    
 wherein a speed change to a third forward speed is realized as the first clutch C 1  is operated, and the first synchro device  40   a  is engaged with the second gear train  30   b;    
 wherein a speed change to a fourth forward speed is realized as the second clutch C 2  is operated, and the third synchro device  40   c  is engaged with the third gear train  30   c;    
 wherein a speed change to a fifth forward speed is realized as the first clutch C 1  is operated, and the first synchro device  40   a  is engaged with the first gear train  30   a;    
 wherein a speed change to a sixth forward speed is realized as the second clutch C 2  is operated, and the fourth synchro device  40   d  is engaged with the third gear train  30   c;    
 wherein a speed change to a seventh forward speed is realized as the first clutch C 1  is operated, the second synchro device  40   b  is engaged with the first gear train  30   a , and the fourth synchro device  40   d  is engaged with the third gear train  30   c ; and 
 wherein a speed change to a eighth forward speed is realized as the second clutch C 2  is operated, the first synchro device  40   a  is engaged with the first gear train  30   a , and the second synchro device  40   b  is engaged with the second gear train  30   b.